1. Field of the Invention
In general, the present invention relates to string trimmer heads that rotate to cut vegetation. More particularly, the present invention relates to the mounting system that is used to connect lengths of trimmer line to the rotating trimmer head.
2. Prior Art Description
The prior art is replete with string trimmers that spin lengths of trimmer line to cut vegetation. String trimmers have trimmer heads that are rotated by either a gasoline motor or an electric motor. Trimmer line extends from the rotating head. The trimmer line typically passes through eyelets that are formed in the trimmer head. When the trimmer line rotates and strikes vegetation, the string bends back toward the trimmer head. This causes a shearing action at the point where the trimmer string exits the trimmer head. Consequently, the trimmer line often wears and breaks at the point where the trimmer line exits the trimmer head. When this occurs, the remaining trimmer line may retreat completely into the trimmer head. If the trimmer head contains an internal supply spool of trimmer line, then the trimmer head must then be disassembled to again extend the trimmer line out of the trimmer head.
In an attempt to reduce the occurrence of trimmer line breaking at the trimmer head interface, trimmer heads have been invented that minimize the shear forces experienced at the trimmer head interface. This is done by connecting the trimmer line to anchor elements that are pivotably connected to the trimmer head. In this manner, when the trimmer line strikes an object and bends back, its mounting anchor pivots and reduces the shear forces. Such prior art trimmer head devices are exemplified by U.S. Patent Application Publication No. 2008/0034724 to Jerez, entitled Powered Disk Preferably With Oscillateable Trimmer Line Hour Mounts.
A problem associated with such prior art trimmer heads is that the anchors that engage the trimmer line are exposed to the cutting environment. Such prior art trimmer line anchors have teeth, sharp edges and other protrusions that enable the anchors to engage the trimmer line. These protrusions have a tendency to catch vegetation and other debris as the trimmer head spins. Once enough vegetation becomes entangled in the anchors, the anchors are no longer free to pivot. The shear forces return and the trimmer line again tends to break at the trimmer head interface.
A need therefore exists for a trimmer line mount that is free to pivot on a mounting head, yet provides no protruding elements that can be immobilized by debris. This need is met by the present invention, as described and claimed below.